GeezerVison

Read insertion order from the iterator's captured values snapshot instead
of re-reading ma_values and asserting against a concurrently changing
size. Retry under the dictionary lock when a value slot has been cleared.

Make insertion-order writes atomic and publish size changes with release
stores, pairing with the iterator's size load. Keep order-byte accesses
relaxed. Add _Py_atomic_store_uint8_release() and
FT_ATOMIC_STORE_UINT8_RELEASE() for this.
(cherry picked from commit 4bb1dad)

Co-authored-by: Neil Schemenauer [email protected]

• Issue: Free-threading: iterating an instance dict can crash during concurrent deletion #158197